import java.util.Scanner;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: 28779
 * Date: 2023-03-03
 * Time: 10:14
 */
public class Test2 {
/*    public static void main(String[] args) {
        int sum = 0;
        int num = 0;
        Scanner sc = new Scanner(System.in);
        while(sc.hasNextInt()) {
            int tmp = sc.nextInt();
            sum += tmp;
            num++;
        }
        System.out.println("sum = " + sum);
        System.out.println("avg = " + sum / num);
        sc.close();
    }*/

    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        //int input = scan.nextInt();
        int i = 2;
        int input = scan.nextInt();
        for (; i < input; i++) {
            if (input % i == 0) {
                System.out.println("不是素数！");
                break;
            }
        }
        if (i == input) {
            System.out.println("是素数！");
        }


    }
}
